Colored Keys is an example toolkit for Minecraft adventure map creators made with Minity,
a scripting language for Vanilla Minecraft.

Place "locks" that will watch for players and turn into redstone when they detect
with the right colored "key", thus triggering any redstone contraption you create.

The locks will remember which way you placed them initially, and detect player in that
direction - look at the position of the slime within the glass block to see which way 
the lock is turned.

To destroy a lock, break its block and kill the slime within. If you don't kill it, the lock will
reactivate after 3 seconds.

More info about Minity: https://minity-script.github.io

The source code of the example: https://github.com/minity-script/minity/tree/main/examples/colored_keys/src